What is the relative mass of protons, neutrons and electrons? - ANS- Protons: 1
Neutrons: 1
Electrons: 1/1840
What is the relative charge of protons, neutrons and electrons? - ANS- Protons: +1
Neutrons: 0
Electrons: -1
What is an atomic number? - ANS- -The number of protons in the nucleus of an atom of an
element.
-All atoms of the same element have the same number of protons.
What is the mass number? - ANS- The total number of protons and neutrons in the nucleus of
an atom of an element.
What is an isotope? - ANS- - Atoms of an element with the same number of protons but a
different number of neutrons.
- Same proton number but different mass number.
What affects the physical properties of an isotope? - ANS- -Mass of the atom affects physical
properties, so isotopes will have slightly different physical properties e.g. different densities,
rates of diffusion.
What affects the chemical properties of an isotope? - ANS- -Number and arrangement of
electrons determine the chemical properties, so isotopes have the same chemical properties.
What is the relative atomic mass? - ANS- - Ar, is the AVERAGE mass of an atom of an element
relative to 1/12th of the mass of an atom of carbon-12.
- not usually a whole number.
What is the relative isotopic mass? - ANS- - The mass of an atom of an isotope, compared to
1/12th of the mass of an atom of carbon-12.
- usually a whole number.
What is the relative molecular mass? - ANS- - Average mass of a molecule compared to 1/12th
of the mass of an atom of carbon-12.
What is the relative formula mass? - ANS- - Average mass of a formula unit compared to 1/12th
of the mass of an atom of carbon-12.
, Difference between RMM and RFM? - ANS- RMM: used when referring to simple molecules.
Find RMM by adding the RAM of all the atoms in the molecule.
RFM: used for ionic compounds (or giant covalent e.g SiO2).
To find RFM, add up RAM of all the ions or atoms in the formula.
How to calculate relative atomic masses from isotopic abundances? - ANS- 1. Multiply the
relative isotopic mass by its % relative isotopic abundance.
2. Add the products together.
Divide by 100 (as its % abundance)
How to use mass spectrometry to work out relative atomic masses? - ANS- 1. Multiply the
relative isotopic mass by its relative isotopic abundance. (not % abundance)
2. Add up the results.
3. Divide by the sum of the isotopic abundances.
How to calculate isotopic mass from relative atomic mass? (if you are given 2 out of 3) - ANS-
1. Work out the abundance of the final isotope (if you don't know it).
2. Use the formula for calculating RAM from RIM & % relative isotopic abundance.
3. Rearrange the formula to work out the isotopic mass of the missing element.
How to predict the mass spectra for diatomic molecules? - ANS- 1. Express the abundances as
decimals.
2. Create a table showing all the possible molecules that could be formed.
3. For each molecule, multiply the decimal abundances of the isotopes to get the relative
abundance of each one.
4. Look for molecules in the table that are the same, if they are, add up their abundances.
5. Divide all the relative abundances by the smallest relative abundance to get the smallest
whole number ratio.
6. Use the RMM of the molecules to predict the mass spectrum.
What are the steps in Mass Spectrometry? - ANS- 1. Vaporisation
2. Ionisation
3. Atomisation
4. Deflection
5. Detection
How to use mass spectra to identify compounds? - ANS- - to find the RMM of a compound, look
at the molecular ion peak (M peak).
- the m/z value is the molecular mass of the compound, you can use this to predict the
compound.
What are electrons grouped together in? - ANS- - quantum shells (energy levels)
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